Apparatus has heretofore been marketed by applicant's assignee for use as a training aid in theory and practice of hydromechanical fluid power systems. In such apparatus, a plurality of hydromechanical devices, such as fluid-powered hydraulic motors, valves and cylinders, are mounted on a vertical panel carried by a wheeled frame. A hydraulic pump is carried by the frame, and is selectively connectable by quick-disconnect hoses to one or more of the hydromechanical devices. All components are standard industrial devices with which the laboratory or classroom trainee thus becomes familiar through a series of exercises or problems set by an instructor or instruction manual. For training in electrohydraulics, which represents the current trend in the fluid power industry, an electrohydraulic servo trainer module has been provided as a separate unit or as an accessory to the standard hydromechanical trainer.
U.S. Pat. No. 5,009,067 assigned to the assignee hereof discloses apparatus for training an operator in theory and practice of electrohydraulic control systems. The apparatus includes a plurality of electrohydraulic devices for performing hydraulic operations as differing functions of associated electronic control signals. A plurality of differing electronic controllers are adapted to generate electronic control signals to operate the electrohydraulic devices. The electronic controllers bear graphic indicia identifying the controller and associating each controller with corresponding electrohydraulic devices on the training unit. Each controller has a plurality of available input, output and control connections, which may be selectively interconnected with each other and with the electrohydraulic devices by suitable cables for configuring the controller and associated devices with a multiplicity of differing operating modes. The electrohydraulic devices are connectable by quick-disconnect hoses to a fluid power source carried by the trainer, and are associated with indicia for generating a visually observable indication of operation of the devices, so that an operator can observe effects of differing electronic control configurations on the devices.
Although the apparatus described above and discussed in the noted patent have met with substantial acceptance and success in both the academic and industrial training environments, further improvements remain desirable. In particular, both of such apparatus are fairly large, embodying a multiplicity of hydraulic and/or electronic apparatus. What is needed, and what the present invention seeks to provide, is a small training unit that may be lifted manually and transported in the trunk of a car, for example, so as to be readily transportable to training sites and/or a student's home for practice. Another object of the present invention is to provide a small and readily portable electrohydraulic trainer of the described character that emphasizes training in the electronic control aspects of electrohydraulics, as distinguished from the hydromechanical aspects of electrohydraulic systems. Yet another object of the present invention is to provide a trainer of the described character that is economical to manufacture, and yet is versatile in terms of capability for training a student or technician in a variety of electronic control situations, and that realistically simulates situations that the trainee may encounter in the field while at the same time providing a user-friendly mechanism for enhanced trainee understanding of electronic control theory and practice.